.\" -*- nroff -*-
.\" Copyright 2013 Los Alamos National Security, LLC. All rights reserved.
.\" Copyright (c) 2010-2015 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2007-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" Copyright (c) 2020      Google, LLC. All rights reserved.
.\" $COPYRIGHT$
.TH MPI_Isend 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Isend\fP \- Starts a standard-mode, nonblocking send.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Isend(const void *\fIbuf\fP, int\fI count\fP, MPI_Datatype\fI datatype\fP, int\fI dest\fP,
	int\fI tag\fP, MPI_Comm\fI comm\fP, MPI_Request\fI *request\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ISEND(\fIBUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR\fP)
	<type>	\fIBUF\fP(*)
	INTEGER	\fICOUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Isend(\fIbuf\fP, \fIcount\fP, \fIdatatype\fP, \fIdest\fP, \fItag\fP, \fIcomm\fP, \fIrequest\fP, \fIierror\fP)
	TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: \fIbuf\fP
	INTEGER, INTENT(IN) :: \fIcount\fP, \fIdest\fP, \fItag\fP
	TYPE(MPI_Datatype), INTENT(IN) :: \fIdatatype\fP
	TYPE(MPI_Comm), INTENT(IN) :: \fIcomm\fP
	TYPE(MPI_Request), INTENT(OUT) :: \fIrequest\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
buf
Initial address of send buffer (choice).
.TP 1i
count
Number of elements in send buffer (integer).
.TP 1i
datatype
Datatype of each send buffer element (handle).
.TP 1i
dest
Rank of destination (integer).
.TP 1i
tag
Message tag (integer).
.TP 1i
comm
Communicator (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
request
Communication request (handle).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_Isend starts a standard-mode, nonblocking send. Nonblocking calls allocate a communication request object and associate it with the request handle (the argument request). The request can be used later to query the status of the communication or wait for its completion.
.sp
A nonblocking send call indicates that the system may start copying data out of the send buffer. The sender should not modify any part of the send buffer after a nonblocking send operation is called, until the send completes.
.sp
A send request can be determined being completed by calling the MPI_Wait, MPI_Waitany, MPI_Test, or MPI_Testany with request returned by this function.

.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

.SH SEE ALSO
MPI_Send
MPI_Wait
MPI_Waitany
MPI_Test
MPI_Testany
.br

